Cytokines generally stimulate proliferation or differentiation of cells of the hematopoietic lineage or participate in the immune and inflammatory response mechanisms of the body. Examples of cytokines which affect hematopoiesis are erythropoietin (EPO), which stimulates the development of red blood cells; thrombopoietin (TPO), which stimulates development of cells of the megakaryocyte lineage; and granulocyte-colony stimulating factor (G-CSF), which stimulates development of neutrophils. These cytokines are useful in restoring normal blood cell levels in patients suffering from anemia, thrombocytopenia, and neutropenia or receiving chemotherapy for cancer.
The interleukins are a family of cytokines that mediate immunological responses. Central to an immune response is the T cell, which produce many cytokines and adaptive immunity to antigens. Cytokines produced by the T cell have been classified as type 1 and type 2 (Kelso, A. Immun. Cell Biol. 76:300-317, 1998). Type 1 cytokines include IL-2, IFN-γ, LT-α, and are involved in inflammatory responses, viral immunity, intracellular parasite immunity and allograft rejection. Type 2 cytokines include IL-4, IL-5, IL-6, IL-10 and IL-13, and are involved in humoral responses, helminth immunity and allergic response. Shared cytokines between Type 1 and 2 include IL-3, GM-CSF and TNF-α. There is some evidence to suggest that Type 1 and Type 2 producing T cell populations preferentially migrate into different types of inflamed tissue.
The immune system is the body's primary defense against diseases caused by pathogens, namely bacteria, viruses, fungi etc, as well as against diseases caused by abnormal growth of the body's own cells and tissues (i.e. cancerous tumors). Normally, the immune system is able to distinguish between the body's normal cells or “self” and foreign pathogens or abnormal cells or “non-self”. The processes by which the immune system refrains from reacting to one's own body is called tolerance. Sometimes, the immune system loses the ability to recognize “self” as normal and the subsequent response directed against the tissue or cells, results in loss of tolerance, a state of autoimmunity. The pathologies resulting from autoimmunity often have serious clinical consequences and are one of the major health problems in the world, especially in developed nations.
One example of such an autoimmune disorder is multiple sclerosis (MS), a progressive disease of the central nervous system (CNS). In MS patients, the patient's own immune system destroys myelin, the protective layer that surrounds and insulates the nerve fibers in the brain and spinal cord. The destruction of the myelin sheath leads to disruption of neurotransmission and scarring damage to the nerve fibers. The end result is the manifestation of numerous symptoms in the affected patient including tingling or numbness, slurred speech, impaired vision, vertigo etc. Over the course of the disease, there is loss of strength in the extremities, leading to problems with movement and in the most severe cases, leading to paralysis of the limbs. Based on clinical diagnosis, there are currently four types of MS classifications, based on which part of the brain or spinal cord are affected, severity, frequency of attacks etc.
Current therapies for MS include corticosteroid drugs (to alleviate symptoms of acute episodes), as well as other drugs like IFN-β and Novantrone®. Novantrone® has been approved for late stage MS patients, specifically for whom other therapies have not worked. Novantrone® is cytotoxic to most cells and therefore as one would expect, has an array of side effects and is toxic at doses required for the maximal therapeutic effects. IFN-β is also toxic, limiting dosage of the drug in MS patients. Furthermore, continuous use of these drugs has been shown to desensitize patients to further use of the same drug, thereby limiting the ability to use these drugs as long term therapeutics.
Of particular interest, from a therapeutic standpoint, are the interferons (reviews on interferons are provided by De Maeyer and De Maeyer-Guignard, “Interferons,” in The Cytokine Handbook, 3rd Edition, Thompson (ed.), pages 491-516 (Academic Press Ltd. 1998), and by Walsh, Biopharmaceuticals: Biochemistry and Biotechnology, pages 158-188 (John Wiley & Sons 1998)). Interferons exhibit a variety of biological activities, and are useful for the treatment of certain autoimmune diseases, particular cancers, and the enhancement of the immune response against infectious agents, including viruses, bacteria, fungi, and protozoa. To date, six forms of interferon have been identified, which have been classified into two major groups. The so-called “type I” IFNs include IFN-α, IFN-β, IFN-ω, IFN-δ, and interferon-τ. Currently, IFN-γ and one subclass of IFN-α are the only type II IFNs.
Type I IFNs, which are thought to be derived from the same ancestral gene, have retained sufficient similar structure to act by the same cell surface receptor. The α-chain of the human IFN-α/β receptor comprises an extracellular N-terminal domain, which has the characteristics of a class II cytokine receptor. IFN-γ does not share significant homology with the type I IFN or with the type II IFN-α subtype, but shares a number of biological activities with the type I IFN.
Clinicians are taking advantage of the multiple activities of interferons by using the proteins to treat a wide range of conditions. For example, one form of IFN-α has been approved for use in more than 50 countries for the treatment of medical conditions such as hairy cell leukemia, renal cell carcinoma, basal cell carcinoma, malignant melanoma, AIDS-related Kaposi's sarcoma, multiple myeloma, chronic myelogenous leukemia, non-Hodgkin's lymphoma, laryngeal papillomatosis, mycosis fungoides, condyloma acuminata, chronic hepatitis B, hepatitis C, chronic hepatitis D, and chronic non-A, non-B/C hepatitis. The U.S. Food and Drug Administration has approved the use of IFN-β to treat multiple sclerosis, a chronic disease of the nervous system. IFN-γ is used to treat chronic granulomatous diseases, in which the interferon enhances the patient's immune response to destroy infectious bacterial, fungal, and protozoal pathogens. Clinical studies also indicate that IFN-γ may be useful in the treatment of AIDS, leishmaniasis, and lepromatous leprosy.
IL-28A, IL-28B, and IL-29 comprise a recently discovered new family of proteins that have sequence homology to type I interferons and genomic homology to IL-10. This new family is fully described in co-owned PCT application WO 02/086087 and Sheppard et al., Nature Immunol. 4:63-68, 2003; both incorporated by reference herein. Functionally, IL-28 and IL-29 resemble type I INFs in their ability to induce an antiviral state in cells but, unlike type I IFNs, they do not display antiproliferative activity against certain B cell lines.
Mature T cells can be activated, i.e., by an antigen or other stimulus, to produce, for example, cytokines, biochemical signaling molecules, or receptors that further influence the fate of the T cell population.
B cells can be activated via receptors on their cell surface including B cell receptor and other accessory molecules to perform accessory cell functions, such as production of cytokines. B cell activation results in the production of antibodies that can bind to immunogenic cell-surface proteins on tumor cells and initiate complement-mediated cell lysis, bridge NK cells or macrophages to the tumor for antibody-dependent cell-mediated cytotoxicity (ADCC), interfere with tumor cell growth by blocking survival or inducing apoptotic signals, or increase immunogenicity by facilitating the uptake and presentation of tumor antigens by APCs. Thus, enhancing B cell responses in vivo has the potential to promote antitumor activity (Blattman et al., Science, 305:200-205 (Jul. 9, 2004)).
Therefore, agents which can augment natural host defenses against tumor induction or progression may increase remission rates and enhance survival of patients, without the cytotoxic side effects of prior methods.
The present invention provides such methods for treating solid tumors, lymphomas, and autoimmune disorders by administrating IL-28A, IL-28B, or IL-29 compositions that may be used as a monotherapy or in combination with chemotherapy, radiation therapy, small molecules or other biologics. These and other uses should be apparent to those skilled in the art from the teachings herein.